Detailed changes:
- use domain config in separate file (not embeded in savefile)
- DispVM domain config generated from dvm.conf (introduced by previous patches) by qubes_restore
- use call 'xl restore' to restore domain (instead of command to xend)
- additional parameter to qubes_restore - config template
- minor changes (xenstore perms, block-detach without /dev/ prefix, etc)
This is core part of migration. Things not migrated yet:
- DispVM (qubes_restore needs to be almost rewritten)
- VM xen config files should be fixed (use "script:" prefix in block device description, perhaps generate this files on VM start)
Huge, slow xend not needed any more, now it conflicts with libxl
